I’m obviously not sure how it worked out before unification, but getting rid of IRMC just pushes the problem right, no?
Each L1 staffs up their needs to…somewhere and they get approved. But at some point, some organization (TB or other) will have to say “we have the $ for this, but not that”. With IRMC, which is presumably DND-internal, the rack-and-stack is at a lower level than having to get to the point of TB, just to essentially be racked-and-stacked at the Govt level.
I could be totally wrong though.